21's without aero can already be done. Just order the 21's and they'll be delivered with aero covers, which you can remove in 2 minutes. The service centers sell center caps too.I’ve seen quite a few range and efficiency tests done, but 2 I’m still waiting for are no tonneau and 21s without aero covers. Anybody know if these have been done?
Not counting towing, it seems the big efficiency killers are alignment, tire inflation / balance, speed >60 mph, and mountainous terrain. I was shocked that my 20" ATs could get 2.51 mi/kWh on a round trip on I-5 between Seattle and Everett (AP drive mode, tonneau open). I was testing efficiency by driving as steady a speed as possible in the right lane, with occasional bursts to pass or merge. A/C was on low, Billie Eilish radio was on high, and the outside temp was 50⁰F with no wind.haven’t seen much of a different in any of the scenarios. Maybe a .1mi/kWh difference with the tent. But all about the same, 2.1-2.2 with the 20” tires.